It is the room where Colin Firth as King George VI learned to overcome his stammer, a scene watched by millions of film fans.

But it can be revealed that the set of Lionel Logue's clinic has been the scene of wild parties organised by the house's owner, Edward Davenport, including being hired out for "sex parties".

Many of the important scenes of The King's Speech, featuring Firth, Geoffrey Rush as Logue and Helena Bonham Carter as the Queen Mother, were filmed inside 33 Portland Place, Marylebone, the £20million Georgian home of Davenport, a self-styled lord.

It is believed the film's creators paid thousands of pounds to use the flamboyant party organiser's 110-room house. The scenes where Firth is coached by Rush were shot in a room that had previously been the backdrop for Davenport's raucous parties attended by the likes of Kate Moss, Naomi Campbell and Cher.

The film's producers were reportedly so pleased with the building that they also used it as the location for 145 Piccadilly, home of the Duke and Duchess of York before Edward VIII's abdication.

Davenport, who is facing charges over an alleged £12million loan fraud and claims of money laundering, was today said by friends to have been "delighted" that filming took place at his home.

Frederick Porter, general manager of 33 Portland Place, said: "Edward was living there during part of the filming. One scene was filmed in his bedroom. Edward is a great supporter of films. He is extremely proud to have been involved."

Mr Porter shrugged off the issue of sex parties, saying: "Everyone in the film industry knows what goes on in there. Everybody would like to be at one of these parties. They are very well-run events. The people who are invited are all like-minded. There were no sex parties while the filming was going on, of course."

Last April, Westminster council discovered that the five-floor property had been used to host a commercial sex party which charged £90 on arrival.

Davenport was told the masquerade ball and "porn disco" breached planning guidelines, and was banned from hosting events. But this month the Court of Appeal granted him permission to challenge the ruling and a judge lifted the injunction that stopped the parties.

Davenport divides his time between Monaco, where he says he is a tax exile, and the Georgian property in central London - once the High Commission of Sierra Leone. On his website Davenport can be seen in photographs rubbing shoulders with Hugh Grant, Simon Cowell, Victoria Beckham and Sarah Ferguson.

He owns a private jet and cars including a Ferrari 360 Spider, an Aston Martin Virage Volante, a Rolls-Royce Phantom and a Lamborghini.

A local resident, who asked not to be named, said: "The room where Colin Firth has all his elocution lessons is exactly the same room where sex parties and porn discos have been held. For such a royal film, it certainly isn't a very regal setting." A spokesman for the film today confirmed much of the film was shot in 33 Portland Place but said the location's owner, or any parties that had gone on there, were "not something that was taken into account".

Davenport's name is listed as Lord Edward Davenport on legal papers, although he says his title is Lord of the Manor of the village of Giffords. He says he inherited the title, though it is claimed that he bought it.